Corrosion inhibition composition for pipelines, process of elaboration and synthesis

ABSTRACT

Compounds and compositions are used as corrosion inhibitors for pipelines for crude oil containing water with high salt concentrations. The inhibitors are ionic liquids, imidazoles, benzotriazoles, and mixtures thereof. The composition includes two or more members of the inhibitors with a solvent. The inhibitors reduce corrosion of metallic surfaces of the pipelines containing crude oil having 0.2 and 40 wt % water, 10,000 to 70,000 ppm salt, and 9 to 600 ppm hydrogen sulfide. A synergic effect is provided by two or more different inhibitors. This synergy is derived from interactions with the metallic surface, among themselves or with the corrosive medium depending on the chain length, to inhibit the corrosion with decrease of the formulation dose. The composition can be a ternary formulation of the three families or two components of one family and a third component of a different family.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit and priority under 35 U.S.C. § 119to Mexican Patent Application No. MX/a/2013/012611 with a filing date ofOct. 29, 2013, the disclosure of which is incorporated herein byreference in its entirety.

FIELD OF THE INVENTION

The present invention relates to the synthesis of basic compounds, thepreparation of compositions and its application as corrosion inhibitorsfor pipelines that transport, besides of crude oil, associatedcongenital water containing high salt concentrations; the inhibitors arebasically constituted by compounds of molecular structure families suchas: imidazoles, benzotriazoles and ionic liquids; said formulations caninclude two or more components of each family and can use as alcoholsolvents, xylene, toluene or mixtures thereof.

The inhibitors object of the present invention control the corrosion ofmetallic surfaces of the pipelines containing concentrations ofcongenital water from 0.2 up to 40% by weight, salt concentrationbetween 10,000 and 70,000 ppm and concentration of hydrogen sulfidebetween 0 and 600 ppm, by means of the synergic effect between two ormore components of the same family, or two or more different molecularstructure families; this synergy is derived from its interactions withthe metallic surface, among themselves or with the corrosive mediumitself due to its chemical, physical and transportation properties,based on the length of the involved chain, that improves corrosioncontrol achieving the simultaneous decrease of dosing of formulations.Whereas, the ternary formulations use a component of each one of thethree families or two components of the same family and a thirdcomponent belonging to the second family of molecules. In all cases, theformulations can include solvents as xylene, methanol and toluene, or amixture of two or three of them.

The application of these compounds and formulations is focused, but notlimited to its use as corrosion inhibitors in typical transportationenvironments of crude oil and petroleum industry generally.

BACKGROUND OF THE INVENTION

Corrosion inhibitors are compounds or formulations of chemical compoundswherein the active part blocks or modifies the electronic transferprocess, responsible of the corrosion phenomena, between the metallicsurface and the surrounding medium. In the petroleum industry, its useis generalized to control metal corrosion in a wide variety of mediumsand conditions. Independently of the system, the interaction between theactive component and the metallic surface plays a determining role inits development and consequently in the corrosion control; saidinteraction depends on the chemical properties of the active compounddepending on its molecular structure, on physical and chemicalproperties of the metal and its own interaction with the surroundingmedium; furthermore, of the operation conditions such as systempressure, temperature and hydrodynamics.

In the particular case of pipes for the transportation of crude oil(pipelines), the control of the internal corrosion is complicated mainlyby the frequent variations present in the type of the transported crude,as well as in the water, salts and dissolved gases contents;nevertheless, the use of inhibitors is still the more profitablealternative to face it.

Among the main chemical families that have been used to inhibitcorrosion in pipelines are nitrogenous compounds such as ammoniumquaternary salts, amines, amides and including amino acids; particularlythe use of fat imidazolines and fat amines as corrosion inhibitors inthe petroleum industry is well known. Generally, it is accepted thatthese compounds work upon absorption forming a protecting film over themetallic surface; nevertheless, independent of the inhibitor used, thesealso have limitations.

In the literature that mentions the use of corrosion inhibitors withspecific application for hydrocarbons transport, are the followinginternational patents:

U.S. Pat. No. 7,057,050 refers to the preparation of novel corrosioninhibitors imidazoline base and its use to inhibit corrosion in metallicflow lines. According to the patent, the inhibitors are a series of newcorrosion inhibitors based on imidazoline base substituted withacrylates, of the following formula:

Wherein R₁ is an alkyl radical having from 2 to 8 carbon atoms; R₂ is aradical derived from a fatty acid, and R₃ is a radical derived from anunsaturated acid.

U.S. Pat. No. 7,160,507 relates to an additive and a method of corrosioninhibition on devices used for the recovery, transportation andprocessing of crude oil; the inhibitor comprises an alkoxylatedquaternary compound of the formula:

where R₁ and R₂ are independently groups of the formula—(B)—(O-A)_(n)-O—CO—R₅ or -(A-O)_(n)—(C)—CO—O—R₅; R₃ is C₁- to C₃₀-alkylor C₂ to C₃₀-alkenyl; R₄ is an organic radical with 1 to 100 atomsoptionally containing heteroatoms; R₅ is an alkyl or an alkenyl; n is anumber from 1 to 20; A is an alkylene group; B is an alkylene group, Cis a C₁- to C₃₀-alkylene and X is an anion.

In patent application U.S. Pat. No. 0,084,612 A1, a method forinhibiting corrosion in metallic surfaces used in manufacture,transportation, storage and separation of crude oil and gas isdescribed; the method comprises adding the fluid a sufficient quantityof a synergist, when H₂S is present in the fluid, or no synergist whenH₂S is present in the fluid and a composition comprising the followingformula and salts thereof:

Wherein R₁ and R₃, C_(n)H_(2n+1) wherein n=0 to 12; benzyl; or H. R₂ isa C₁ to C₂₂ alkyl. X— is a halogen or a carboxylate and is only presentwhen R₁ and R₃ are present. Y is (CH₂)_(n) with n=1 to 8 and wherein R₃and R₁ cannot be hydrogen at the same time.

Another structure mentioned in this patent application is:

wherein R₁ and R₂ are similar to the above structure and isC_(n)H_(2n+1) wherein n=0 is a C₁ to C₂₂ alkyl. X—═Cl, Br or I.

WO 157234 relates to novel quaternary-nitrogen compounds in itsstructure and formulations used by these compounds that are useful ascorrosion inhibitors in the gas and petroleum industry. The quaternarynitrogen-containing corrosion inhibitors have the following formula:

Wherein:

is an aromatic, nitrogen-containing ring of 5 to 14 atoms, optionallycontaining an additional N, O or S ring atom in the additional N ring orcan be substituted with one or more alkyl, alkenyl, aryl, arylalkyl,cycloalkyl, amine, aminoalkyl, alkoxy, hydroxyalkyl or cyano groups, ora mixture thereof; Y is a group of formula —OC(O)R₁; L is an C₁-C₁₀alkyl, C₂-C₂₀ alkenyl of the formula —CH₂CH(OR₂)CH₂—; R₁ is C₈-C₂₀alkenyl; R₂ is H or —C(O)R₁; R₃ and R₄ are independently selected fromH, alkyl, alkenyl, amino, aminoalkyl, alkoxy, hydroxyalkyl or cyano; andX is Br, Cl or I.

WO 091429 relates to corrosion inhibition in ferrous and non-ferrousmetals in aqueous-based environments by the use of formulations that useat least two mercaptan compounds of the following formulae:

wherein X is C, N, O or S; R₁, R₂, R₃ y R₄ are independently H ormethyl; n and m are independently integers from 1 to 5 and p and q areindependently integers from 1 to 4.

wherein m is an integer from 3 to 4; and

wherein m is an integer from 1 to 4; and n=4−m.

WO 128313 relates to a corrosion inhibitor for use in the oil and gasexploration, recovery and processing industries consisting of aquaternary ammonium compound of the formula:

wherein R is C₁₋₆ alkyl, C₂₋₆ alkenyl, aryl, arylalkyl; X, Y and Z areeach independently H or R₁CO— group, provided that at least one of X, Y,Z is R₁CO— where R1 is a C₅₋₂₃ alkyl or alkenyl containing 0, 1, 2, or 3double bounds; D is C₂₋₆ alkylene; E is C₂₋₄ alkylene; p, q and r areindependently integers from 0 to 20, with the proviso that p+q+r=3 to20; and A is an anion.

Other patent applications related to corrosion inhibitors withapplication in crude oil transportation are patent application WO 000895that refers to a polymeric product obtained by the reaction betweenalkoxylated fat amine and a dicarboxylic acid derivative, whereas patentapplication WO 028542 refers to the use of polyamine polyester compoundsand polyquaternary polyester ammonium as corrosion inhibitors in thetransportation of crude oil and in the oil and gas wells.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to clearly understand the evaluation of the synthesis ofindividual chemical structures; as well as the evaluation of theinhibition efficiency to corrosion of the corrosion inhibitionformulation, object of the current invention, that is why, reference ismade to the FIGURE attached without limiting the scope of the invention:

FIG. 1 illustrates the electrochemical cell used in the evaluation ofcorrosion inhibition evaluation.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to synthetizing individual chemicalcompounds and providing corrosion inhibitor compositions formulated fromsynthesized structures that belong to different chemical families:imidazoles, benzotriazoles and ionic liquids. The basic criteria for thedesign of said formulations is based on the knowledge of the effect thathas a particular structure over the modification of involved phenomenain the corrosion process and synergy that is generated using togetherwith one or more molecular structures belonging to a particular family,in this case the difference is mainly centered on the chain length or onstructures belonging to one or more different families, situation wherethe inherent functionality to each compound family is taken advantage.The procedure for obtaining each formulation comprises the followingsteps: a synthesis step of the structures used as an active component; astep of incorporation of one, two or three active components of the sameor different chemical structure family; a step of incorporation of thesolvent and a step of stirring to obtain the complete integration of theformulation.

The composition object of the current invention are useful to controlthe internal corrosion in pipelines transporting crude oil wherein thecontent of associated water is from 0.2 to 40% by weight and theconcentration of inorganic salts (i.e. chlorides, sulfates, carbonates,among others) ranges from 10,000 and 70,000 ppm and wherein there isevidence of the presence of H₂S and O₂, as dissolved gases.

Two of the families of the compounds involved in the current inventionbelong to azoles and are mainly amine derivatives of imidazole andbenzotriazole whereas the third belongs to ionic liquids; the structuralcharacteristics of each family is described below:

Wherein R is a saturated or unsaturated hydrophobic hydrocarbon chaincontaining 2 to 25 carbon atoms and can be linear or branched. The chaincan be an alkyl.

R₁ is hydrogen or a linear or branched alkyl radical containing from 1to 5 carbon atoms.

Wherein R is a saturated or unsaturated hydrophobic hydrocarbon chaincontaining 2 to 25 carbon atoms and can be linear or branched,inclusively it can have internal substituents that increase itscorrosion inhibition properties of the original structure. Examples ofinternal substituents are the amide and amine groups

Wherein R is a saturated or unsaturated hydrophobic hydrocarbon chaincontaining 2 to 25 carbon atoms and can be linear or branched.

R₁ is hydrogen or a linear or branched alkyl radical containing from 1to 5 carbon atoms; X is a halogen, preferably Cl, Br or I.

This invention also considers the compositions where compounds from theimidazoles, benzotriazoles and ionic liquid families are involved; thesemixtures result in a binary or tertiary combination among members of thesame or different families.

In the case of binary mixtures of the same families, the currentinvention refers to, but is not limited to, the following cases:

Formulations composed by the members of the imidazole amine derivativesfamily, family A, with general formula

Wherein, for the first member of the composition, component A1, R is asaturated or unsaturated hydrophobic hydrocarbon chain containing from 2to 10 carbon atoms but preferably from 4 to 8 carbon atoms; whereas forthe second member of the composition, component A2, R is a saturated orunsaturated hydrophobic hydrocarbon chain containing from 11 to 25carbon atoms, more preferably from 12 to 20 carbon atoms. In both cases,the hydrophobic hydrocarbon chain can be linear or branched and R₁ is,also for both members, a hydrogen or a linear or branched alkyl radicalcontaining from 1 to 5 carbon atoms. The imidazole forms the cation andthe Cl, Br and I form the anion.

The compositions are mixtures of components A1 and A2 with a ratio thatcan be of 1:1, 1:2, 1:3, 3:1, 2:1.

Formulations composed by two members of amine derivatives of thebenzotriazole family, family B, with general formula

Wherein, for the first member of the composition, component 81, R is asaturated or unsaturated hydrophobic hydrocarbon chain containing from 2to 10 carbon atoms, but preferably from 6 to 10 carbon atoms and it canbe linear or branched or inclusively can have internal substituents thatincrease the corrosion inhibition properties of the original structure;whereas, for the second member of the composition, component 82, R is asaturated or unsaturated hydrophobic hydrocarbon chain containing from11 to 25, but preferably from 14 to 18 carbon atoms and can be linear orbranched and inclusively can have internal substituents that increasecorrosion inhibition properties of the original structure. Examples ofinternal substituents are the amide and amine groups.

The compositions are mixtures of components B1 and B2 with a ratio thatcan be of 1:1, 1:2, 1:3, 3:1, 2:1.

Formulations composed by two members of amine derivatives from the ionicliquid family, family C, with general formula

Wherein, for the first member of the composition, component C1, R is asaturated or unsaturated hydrophobic hydrocarbon chain containing from 2to 10, but preferably from 4 to 8 carbon atoms and can be linear orbranched; whereas for the second member of the composition, componentC2, R is a saturated or unsaturated hydrophobic hydrocarbon chaincontaining from 11 to 25, but preferably from 14 to 18 carbon atoms andit can be linear or branched.

For both components, R₁ is hydrogen or a linear or branched alkylradical containing from 1 to 5 carbon atoms and X is halogen, preferablyCl, Br or I.

The compositions are mixtures of components B1 and B2 with a relationthat can be of 1:1, 1:2, 1:3, 3:1 and 2:1.

In case of binary mixtures of different families, the current inventionrefers to, but is not limited to the following cases:

Formulations composed by members of amine derivatives from the imidazoleand benzotriazole families.

The compositions are mixtures of the components A1 and B1; A1 and B2; A2and B1 and A2 and B2, but preferably A2 and B1, with the ratio from 1:3to 3:1.

Formulations composed by members of amine derivatives from the imidazoleand ionic liquid families.

The compositions are mixtures of the components A1 and C1; A1 and C2; A2and C1 and A2 and C2, but preferably A2 and C1, with the ratio from 1:3to 3:1.

Formulations composed by members of amine derivatives from thebenzotriazoles and ionic liquid families.

The compositions are mixtures of the components B1 and C1; B1 and C2; B2and C1 and B2 and C2, but preferably B2 and C2, with the ratio from 1:3to 3:1.

In the case of ternary mixtures of molecules belonging to the same ordifferent families, the current invention refers to, but is not limitedto the following cases:

The compositions are mixtures of the following components A1, B1 and C1;A1, B1 and C2; A1, B2 and C1; A1, B2 and C2; A2, B1 and C1; A2, B1 andC2; A2, B2 and C1; A2, B2 and C2; A1, A2 and B1; A1, A2 and B2; A1, A2and C1; A1, A2 and C2; B1, B2 and A1; B1, B2 and A2; B1, B2 and C1; B1,B2 and C2; C1, C2 and A1; C1, C2 and A2; C1, C2 and B1; and C1, C2 andB2, but preferably A1, A2 and C1; A1, A2 and C2 and B1, B2 and C1 andB1, B2 and C2, with molar ratio from 1:1:1 to 2:1:1, 1:2:1, 1:1:2.

EXAMPLES

Below are described examples of the synthesis of basic structuresbelonging to the three families involved in corrosion inhibitorformulations and examples of binary and ternary formulations; as well asthe evaluation of corrosion inhibition efficiency of the formulationsand the individual components.

Example 1 Synthesis of Imidazole Amine Derivatives Synthesis ofN-[1H-imidazole-(4-methylidene)]-hexane-1-amine

In a ball flask attached to a cooler with magnetic stirring, are placed25 g of 4-imidazolcarboxaldehyde and 20 mL of methanol (MeOH) are added,are maintained in moderated stirring up to full dissolution; 32.5 mL ofhexylamine are added, maintaining stirring and 15 additional mL of MeOHare added.

The reaction mixture is maintained under reflux for 9 hours at atemperature of 60° C., between the fourth and the sixth reflux hours; aDean-Stark trap is placed to withdraw the H₂O generated during thereaction.

Once concluded the reaction time, it is left at room temperature and thesolvent is evaporated at reduced pressure. The obtained product isyellow oil with a performance of 81%.

Example 2 Synthesis of N-[1H-imidazole-(4-methylidene)]-decan-1-amine

The same procedure described in Example 1 is followed, using 25 mL ofdecylamine instead of hexylamine.

The obtained performance in this case is of 78%.

Example 3 Synthesis of Benzotriazole Amine Derivatives Synthesis ofN-(1H-benzotriazole-1-methyl)-octadecan-1-amine

In a ball flask equipped with magnetic stirring, 17.5 g of1H-Benzotriazole are placed maintaining a moderate stirring, 60 mL ofmethanol (MeOH) are added and stirring is continued for dissolution. 40g of 1-octadecylamine are added, stirring is maintained to obtain aslightly yellow crystalline solution and 20 mL of formaldehyde aqueoussolution are added.

The mixture is maintained under stirring at room temperature during 2hours; the reaction product precipitates as a soft solid, the solvent isremoved by filtration and is dried at a temperature of 110° C. during 2h. The performance is of 79%.

Example 4 Synthesis of N-(1H-benzotriazole-1-methyl)-hexane-1-amine

The same procedure of the Example 3 is followed, using 25 mL of1-hexylamine instead of 1-octadecylamine.

The product is viscous yellow oil with a performance of 89%.

Example 5 Synthesis of Ionic Liquids Synthesis of1-allyl-3-methylimidazolium bromide

In a 100 mL ball flask attached to a cooler and with magnetic stirring,15 g of methylimidazolium dissolved of 25 mL of toluene are added; withthe help of an addition funnel; 30 g of allyl bromide are incorporated,the reaction mixture is stirred and is taken at a temperature of 60° C.,stirring is maintained for 1.0 hour.

The reaction mixture is washed twice with 10 mL of ethyl acetate andfurthermore with 15 mL of ether. The solvent is removed with aRotavapor®.

The obtained product is dried at high vacuum, obtaining a yellow liquidwith a performance of 92%.

Example 6 Synthesis of 1-decyl-3-methylimidazolium bromide

The same procedure described in Example 5 is used, but with thefollowing reagents and quantities:

12 g of methylimidazolium

35 mL of toluene

22 g of bromodecane

The reaction mixture is stirred and is taken to a temperature of 95° C.and is maintained under stirring for 2 hours.

The following steps are similar to those of Example 5. An amber liquidwith a performance of 87.5% is obtained.

Example 7 Evaluation of Corrosion Inhibiting Properties of IndividualStructures and Binary Formulations Object of the Current Invention

Methodology of Evaluation

Evaluation Using Electrochemical Impedance Spectroscopy (EIS)

The evaluation of corrosion inhibiting properties of the individualstructures and binary compositions was carried out in a conventionalelectrochemical cell (E) with a three electrode arrangement as the oneshown in FIG. 1. This cell allows maintaining stirring and constanttemperature during development of measurement.

The inhibiting formulations to be evaluated are added in the desiredconcentration in the test solution (D), whereas a stirring of 2000 rpmand a temperature of 40° C. are maintained. Furthermore, it is submergedin a sample as a steel disk to the carbon previously destroyed with a600 sandpaper, this sample has the function of a work electrode (B) inthe electrochemical cell; the graphite auxiliary counter electrode (C)and the calomel saturated electrode (A) are placed as reference. Thesystem is maintained under stirring and constant temperature for 3hours.

After 3 hours, the electrochemical impedance spectrum is obtained in arange of 10 kHz and 10 mHz frequency and the resistance related tocorrosion and together with that obtained in an identical experiment butonly with the test solution was obtained from this spectrum; thecorrosion inhibition efficiency was calculated.

Evaluation of Behavior Tests

The binary and ternary compositions were evaluated through the followingbehavior tests, specific for this type of product:

Behavior Test Nace ID 182 Method of the Wheel

A sample of carbon steel to API 5L X52 with dimensions of 2.54 cm×1.27cm×0.025 are weighed and a bottle with 180 mL of test solution isplaced, preferably a sample of the system where the inhibitor will beused, or an aggressive saline solution that simulates the acid, basicand neutral environments of the petroleum industry and a specificconcentration of the corrosion inhibitor to be evaluated. The bottle issealed and introduced in a temperature chamber with a 58.4 cm diameterwheel, provided with adequate and sufficient housing for 52 samples(bottles), the temperature of the chamber is increased at the desiredvalue that preferably corresponds to the system operation temperaturewhere the inhibitor is applied; the wheel rotation of 30 revolutions perminute was started during the heating process, that is maintained for a24 hours period once the temperature is achieved.

At the end of the test, the sample is removed and washed consecutivelywith hexane, acetone, water, an inhibited solution of hydrochloric acid,a 5% potassium bicarbonate solution, is cleaned with water and soapusing a plastic firm bristle swab, is rinsed with deionized water, iswashed with acetone and is dried in an oven at 60° C. for one hour, thesample is left to achieve room temperature and is weighed. With thedifference of weight obtained in the sample in experiments without(blank) and with inhibitor, the corrosion inhibition efficiency wascalculated.

Behavior Test ASTM G 185 Rotating Cylinder, Rp/Weight Loss

A cylindrical carbon steel specimen API 5L X52 with dimensions of 0.793cm in radius and 1 cm long, is introduced into the electrochemical cell,as the one shown in FIG. 1 where previously the test solution wasintroduced, that would preferably correspond to a real sample of thesystem in which the inhibitor will be used and a known concentration ofthe inhibitor to evaluate. Rotation and temperature conditions areestablished depending on the system conditions in which the inhibitorwill be used and the corrosion inhibition efficiency is evaluatedrelated to the blank experiment (absence of inhibitor) according to thestandards ASTM D G 1, ASTM D G 3, ASTM D G 5 y ASTM D G 59.

Similar to the method of the wheel, the corrosion inhibition efficiencycan be evaluated by weight loss registering the initial weight of thecylindrical specimen and its weight after the before-mentioned cleaningprocedure.

Table 1 shows the characterization of the waters used as test solutionsin the evaluation that were carried out both with independent structuresand different formulations; whereas Table 2, shows some corrosioninhibitor results obtained with different concentrations of structuresbelonging to the three families, evaluated as the water identified asSP1 in Table 1.

TABLE 1 Characterization of real samples of water related to the crudetransported in pipelines, these samples were used as test solutions invarious evaluations of corrosion inhibition properties of thesynthetized structures and formulations obtained thereof. Analyte, Testsolution mg/L SP1 SP2 SP3 Na 30,000 9,907 Specification K 3,445 117ASTM-D 1141 Ca 1,980 118 “Substitute Ocean Mg 1,245 32 Water” + 600 mg/LH₂S Mn 6.25 0 Sr 1,388 41 Ba 52.1 0.53 Specification Fe 0.22 0.56 ASTM-D1141 Cl 11,510 12,400 “Substitute Ocean SO₄ 2,930 1,310 Water” + 600mg/L NO₃ 2,810 0 H₂S NO₂ 0 0 F 121 13 pH 7.20 7.60 3.5 Corrosion 41.838.0 45.8 NACE ID 182 72 h 45° C., mpa

TABLE 2 Corrosion inhibition efficiencies electrochemically evaluatedwith EIS using the test water SP1. Concentration Inhibition FamilyStructure mg/L efficiency % Imidazole IMC12 2500 95.4 500 80.9 50 23.1IMC14 2500 98.0 500 78.9 50 19.8 IMC18 2500 94.4 500 84.5 50 20.2Benzotriazole BZC6 2500 73.7 500 35.3 50 18.2 BZC10 2500 86.7 500 69.150 10.6 BZC14 2500 96.2 500 97.4 50 55.8 BZC18 2500 98.6 inst 500 96.250 18.5 Ionic liquids MIMC4 2500 76.0 500 61.9 50 15.2 MIMC8 2500 76.2500 58.6 50 10.3 MIMC12 2500 89.3 500 77.7 50 12.4 MIMC16 2500 83.1 50076.5 50 20.3

Example 8 Evaluation of Corrosion Inhibition Properties of BinaryFormulations Preparation of Binary Formulations

In order to improve the corrosion inhibition efficiency thatindividually shows the structures at lower dosages, the followingformulations between members of the same family and two differentfamilies were prepared:

Family IC12C14, wherein component A1 isN-[1H-imidazole-(4-methylidene)]-dodecane-1-amine, whereas the componentA2 is N-[1H-imidazole-(4-methylidene)]-tetradecane-1-amine.

Ratio 1:0 Is prepared weighing 100 g of component A1 and adding 67 mL ofxylene, is moderately stirred to get full integration.

Ratio 3:1 Is prepared weighing 75 g of A1, 67 mL of xylene are addedwhereas it is moderately stirred, 25 g of component A2 are added andstirring is continued to get full integration.

Ratio 1:1 50 g of A1 and 50 g of A2 are weighed, the preparation issimilar to the last one.

Ratio 1:3 25 g of A1 and 75 g of A2 are weighed, the preparation issimilar to the last one.

Ratio 0:1 100 g of A2 are weighed, the preparation is similar to theratio 1:0.

Family BZC6C12, wherein component B1 isN-(1H-benzotriazole-1-methyl)-hexane-1-amine, whereas the component B2is N-(1H-benzotriazole-1-methyl)-dodecane-1-amine.

The same ratio as those of family A are prepared, weighing in this casethe same quantities but of the compounds B1 and B2 using methanol assolvent.

Family MIMC4C18, wherein component C1 is 1-butyl-3-methylimidazoliumbromide, whereas component C2 is 1-octadecyl-3-methylimidazoliumbromide.

The same ratio as those of family A are prepared, weighing in this casethe same quantities but of the compounds C1 and C2 using toluene assolvent.

Family BZC6MIMC4, wherein component A1 isN-(1H-benzotriazole-1-methyl)-hexane-1-amine, whereas component C1 is1-butyl-3-methylimidazolium bromide.

The same ratio as those of family A are prepared, weighing in this casethe same quantities but of the compounds A1 and C1 using 67 mL of a50/50 mixture of methanol/toluene as solvent.

Family BZC12MIMC18, wherein component A2 isN-(1H-benzotriazole-1-methyl)-dodecane-1-amine, whereas component C2 is1-octadecyl-3-methylimidazolium bromide.

The same ratio as those of family A are prepared, weighing in this casethe same quantities but of the compounds A2 and C2 using 67 mL of a50/50 mixture of methanol/toluene as solvent.

These formulations were evaluated with the same electrochemicalmethodology described in Example 7 using SP1 test solution and a dose of50 mg/L of each one of them, the obtained corrosion inhibition resultsare shown in Table 3.

TABLE 3 Corrosion inhibition efficiencies of binary formulations,electrochemically evaluated with EIS technique using test water SP1 anda dose of 50 mg/L each. Inhibition efficiency, % Family Formulation 1:03:1 1:1 1:3 0:1 Amine IC12C14 95.5 87.0 93.2 92.3 98.0 Imidazole AmineBZC6C12 89.0 85.3 87.4 76.2 82.0 Benzotriazole Ionic liquid MIMC4C1876.0 50.9 70.9 92.0 83.0 Amine BZC6MIMC4 89.0 91.1 90.8 92.2 76.0Benzotriazole/ Ionic liquid Amine BZC12MIMC18 82.0 84.7 81.5 84.0 83.0Benzotriazole/ Ionic liquid

Additionally, the formulations were evaluated by the method of the wheel(Wheel test) according to the NACE ID 182 specification using the testsolution SP3 and a dosage of 50 ppm. Corrosion inhibition efficienciesobtained with this methodology are presented in Table 4.

TABLE 4 Corrosion inhibition efficiencies of binary formulations,evaluated with the method of the wheel (Wheel test) using test water SP3and a dosage of 50 mg/L each. 72 hours of test at 45° C. Inhibitionefficiency, % Family Formulation 1:0 3:1 1:1 1:3 0:1 Amine IC12C14 71.685.4 83.4 87.7 81.9 Imidazole Amine BZC6C12 82.7 82.9 91.4 90.4 59.9Benzotriazole Methyl- MIMC4C18 84.2 85.9 87.3 93.2 82.3 imidazoliumAmine BZC6MIMC4 82.7 81.6 87.0 86.7 84.2 Benzotriazole/ Methyl-imidazolium Amine BZC12MIMC18 59.9 79.8 82.2 84.5 90.3 Benzotriazole/Methyl- imidazolium

Example 9 Evaluation of Corrosion Inhibition Properties of TernaryFormulations Preparation of Ternary Formulations

Formulations of three components are prepared, wherein all componentsmay belong to different families, or two of them belong to the samefamily whereas the other belong to another family.

Family IC12BZC6MIMC4, wherein the component A1 isN-[1H-imidazole-(4-methylidene)]-dodecane-1-amine; the component B1 isN-(1H-benzotriazole-1-methyl)-hexane-1-amine; and the component C1 is1-butyl-3-methylimidazolium bromide.

In order to prepare the 1:1:1 ratio, 33.3 g of A1 are weighed and 22 mLof xylene are added; at moderate stirring, 33.3 g of B1 is added andstirring is continued adding 22 mL of methanol; finally, and maintainingstirring, 33.3 3 of C1 and 34 mL of toluene are added, stirring iscontinued up to complete integration.

Family IC14BZC12MIMC18, wherein component A2 isN-[1H-imidazole-(4-methylidene)]-tetradecane-1-amine; the component B2is N-(1H-benzotriazole-1-methyl)-dodecane-1-amine; and component C2 is1-octadecyl-3-methylimidazolium bromide.

The procedure of the above formulation is followed but using componentsA2, B2 and C2.

Family BZC6C12MIMC4, wherein component B1 isN-(1H-benzotriazole-1-methyl)-hexane-1-amine; component B2 isN-(1H-benzotriazole-1-methyl)-dodecane-1-amine; and component C1 is1-butyl-3-methylimidazolium bromide.

The same procedure of the above formulation is followed but usingcomponents B1, B2 and C1 and methanol as solvent to solubilize compoundsB and toluene.

Family BZC6C12IC14, wherein component B1 isN-(1H-benzotriazole-1-methyl)-hexane-1-amine; component B2 isN-(1H-benzotriazole-1-methyl)-dodecane-1-amine; A2 isN-[1H-imidazole-(4-methylidene)]-tetradecane-1-amine.

The procedure of the above formulation is followed but using componentsB1, B2 and C2.

Family IC12C14BZC12, wherein component A1 isN-[1H-imidazole-(4-methylidene)]-dodecane-1-amine; component A2 isN-[1H-imidazole-(4-methylidene)]-tetradecane-1-amine; and component B2is N-(1H-benzotriazole-1-methyl)-dodecane-1-amine.

The procedure of the above formulation is followed but using componentsA1, A2 and B2 and xylene to solubilize compounds A and methanol assolvents.

Family IC12C14MIMC18, wherein component A1 isN-[1H-imidazole-(4-methylidene)]-dodecane-1-amine; component A2 isN-[1H-imidazole-(4-methylidene)]-tetradecane-1-amine; and component C2is 1-octadecyl-3-methylimidazolium bromide.

The procedure of the above formulation is followed but using componentsA1, A2 and C2 and xylene to solubilize compounds A and toluene assolvents.

The evaluation of the corrosion inhibition efficiency, using a dosage of50 mg/L of these formulations in various behavioral tests and withdifferent media is shown in Table 5.

TABLE 5 Corrosion inhibition efficiencies of ternary formulationsevaluated with test methods: rotating cylinder, wheel (Wheel test) andElectrochemical (EIS) using test solutions SP1, SP2 and SP3, asindicated, and a dosage of 50 mg/L of each formulation. % of corrosioninhibition efficiency Rotating cylinder ASTM G 185 Medium: SP1 Method ofthe wheel EIS Weight NACE ID 182 Medium: Formulation loss Rp SP1 SP2 SP3SP3 IC12BZC6MIMC4 90.8 96.3 95.9 96.6 93.6 99.9 IC14BZC12MIMC18 93.594.7 97.3 95.2 96.1 98.9 BZC6C12MIMC4 96.7 90.5 93.2 90.9 91.7 97.2BZC6C12IC14 91.1 96.1 92.9 94.3 95.0 99.0 IC12C14BZC12 95.8 96.5 91.492.6 93.3 98.3 IC12C14MIMC18 93.1 92.0 90.4 95.4 94.5 99.7

What is claimed is:
 1. A method of inhibiting corrosion of metalsurfaces in contact with crude oil, said method comprising the step ofadding a corrosion inhibiting composition to the crude oil in contactwith the metal surfaces, wherein said corrosion inhibiting compositioncomprises a mixture of at least two different corrosion inhibitingcompounds selected from the group consisting of imidazoles andbenzotriazoles, said imidazoles having the formula:

wherein R is a saturated or unsaturated hydrophobic hydrocarbon chaincontaining 2 to 25 carbon atoms and can be linear or branched; and R₁ ishydrogen or a linear or branched alkyl radical containing from 1 to 5carbon atoms; and said benzotriazoles having the formula:

wherein R is a saturated or unsaturated hydrophobic hydrocarbon chaincontaining 2 to 25 carbon atoms and can be linear or branched.
 2. Themethod of claim 1, wherein said crude oil contains 0.4 to 40% by wt.water and 10,000 to 70,000 ppm inorganic salts, and contains dissolvedH₂S and oxygen.
 3. The method of claim 1, wherein said mixture isselected from the group consisting of; a first imidazole where R is asaturated or unsaturated hydrophobic C₂ to C₁₀ hydrocarbon R₁ is H or alinear or branched alkyl C₁ to C₅ hydrocarbon and a second imidazolewhere R is a saturated or unsaturated hydrophobic C₁₁₋₂₅ hydrocarbon andR₁ is H or a linear or branched alkyl C₁ to C₅ hydrocarbon; and a firstbenzotriazole where R is a saturated or unsaturated hydrophobic C₂ toC₁₀ hydrocarbon and a second benzotriazole where R is a saturated orunsaturated hydrophobic C₁₁ to C₂₅ hydrocarbon.
 4. The method accordingto claim 1, wherein said corrosion inhibiting composition is dispersedin crude oil having a water concentration from 0.2 to 40% by weight; asalt concentration of 10,000 to 70,000 ppm and hydrogen sulfideconcentration from 0 and 600 ppm.
 5. The method according to claim 1,wherein said corrosion inhibiting composition is added to said crude oilin an amount of 500 to 2500 mg/L based on the amount of the crude oil.6. The method of claim 1, where said mixture comprises a first imidazolewhere R is a saturated or unsaturated hydrophobic C₂ to C₁₀ hydrocarbonand a second imidazole where R is a saturated or unsaturated hydrophobicC₁₁ to C₂₅ hydrocarbon.
 7. The method of claim 1, where said corrosioninhibiting mixture comprises a first benzotriazole where R is asaturated or unsaturated hydrophobic C₂ to C₁₀ hydrocarbon and a secondbenzotriazole where R is a saturated or unsaturated hydrophobic C₁₁ toC₂₅ hydrocarbon.
 8. The method of claim 1, wherein said mixturecomprises a first imidazole where R is a saturated or unsaturatedhydrophobic C₁₁ to C₂₅ hydrocarbon and said a first benzotriazole whereR is a saturated or unsaturated hydrophobic C₂ to C₁₁ hydrocarbon.
 9. Amethod of inhibiting corrosion on metal surface in contact with crudeoil, said method comprising the step of adding a corrosion inhibitingcomposition to the crude oil in contact with the metal surfaces, whereinsaid corrosion inhibiting composition comprises a mixture selected fromthe group consisting of; at least one imidazoles and at least onebenzotriazoles; at least one imidazoles and at least one ionic liquids;at least one benzotriazoles and at least one ionic liquids; and at leastone imidazoles, at least one benzotriazoles and at least one ionicliquid, wherein said ionic liquid having the formula

where R is a linear or branched saturated or unsaturated hydrophobichydrocarbon chain containing 2 to 25 carbon atoms; and R₁ is hydrogen ora linear or branched alkyl radical containing from 1 to 5 carbon atoms,and X is Cl, Br or I, and said imidazole having the formula:

wherein R is a saturated or unsaturated hydrophobic hydrocarbon chaincontaining 2 to 25 carbon atoms and can be linear or branched; and R₁ ishydrogen or a linear or branched alkyl radical containing from 1 to 5carbon atoms; and said benzotriazole having the formula:

wherein R is a saturated or unsaturated hydrophobic hydrocarbon chaincontaining 2 to 25 carbon atoms and can be linear or branched.
 10. Themethod of claim 9, wherein said at least one ionic liquid comprises afirst ionic liquid where R is a saturated or unsaturated hydrophobic C₂to C₁₀ hydrocarbon and a second ionic liquid where R is a C₁₁ to C₂₅hydrocarbon.
 11. The method of claim 9, wherein said mixture comprisessaid at least one imidazole where R is a saturated or unsaturatedhydrophobic C₁₁ to C₂₅ hydrocarbon and said at least one ionic liquidwhere R is a linear or branched saturated or unsaturated hydrophobic C₁₁to C₂₅ hydrocarbon.
 12. The method of claim 9, wherein said mixturecomprises said at least one benzotriazole where R is a saturated orunsaturated hydrophobic C_(ii) to C₂₅ hydrocarbon and said at least oneionic liquid where R is a linear or branched saturated or unsaturatedhydrophobic C₁₁ to C₂₅ hydrocarbon.
 13. The method of claim 9, whereinsaid mixture is selected from the group consisting of a mixture of afirst imidazole where R is a saturated or unsaturated hydrophobic C₂ toC₁₀ hydrocarbon, a second imidazole where R is a saturated orunsaturated hydrophobic C₁₁ to C₂₅ hydrocarbon, and said ionic liquidwhere R is a linear or branched saturated or unsaturated hydrophobic C₂to C₁₀ hydrocarbon; a mixture of a first imidazole where R is asaturated or unsaturated hydrophobic C₂ to C₁₀ hydrocarbon, a secondimidazole where R is a saturated or unsaturated hydrophobic C₁₁ to C₂₅hydrocarbon, and said ionic liquid where R is a linear or branchedsaturated or unsaturated hydrophobic C₁₁ to C₂₅ hydrocarbon; a mixtureof a first benzotriazole where R is a saturated or unsaturatedhydrophobic C₂ to C₁₀ hydrocarbon, a second benzotriazole where R is asaturated or unsaturated hydrophobic C to C₂₅ hydrocarbon, and saidionic liquid where R is a linear or branched saturated or unsaturatedhydrophobic to C₁₀ hydrocarbon; and a mixture of a first benzotriazolewhere R is a saturated or unsaturated hydrophobic C₂ to C₁₀ hydrocarbon,a second benzotriazole where R is a saturated or unsaturated hydrophobicC₁₁ to C₂₅ hydrocarbon and said ionic liquid where R is a linear orbranched saturated or unsaturated hydrophobic C₁₁ to C₂₅ hydrocarbon.